Lubricating oils containing amine oxides



3,277,003 LUBRIICATING OILS CONTAINING AMTNE OXEDES .llarnes T. Gragson, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed Feb. 17, 1964, Ser. No. 345,112 8 Claims. (Cl. 25232.7)

This invention relates to lubricating oils containing a novel rust inhibiting agent. In one aspect this invention relates to a method for inhibiting rusting of ferruginous metals in'contact with a lubricating oil. In another aspect" this invention relates to motor oils and other petroleumbased lubricants containing a novel rust-inhibiting additive along with conventional lubricating oil additives.

Substantially all of the motor oils now marketed contain additives to enhance the lubricaing properties of the oils under various operating conditions. In addition to its function of reducing friction between moving metal parts, a lubricant composition must also, in most cases, protect metal surfaces against corrosion during operation of the device being lubricated and must also provide protection against formation of rust during periods when the device is idle and on parts not subjected to friction during operation of the device. Additional additives are frequently incorporated in the lubricant to prevent formation of sludge, to improve the viscosity index of the oil and to lower the pour point of certain oils. Other more specialized additives are incorporated under certain conditions. Bearing corrosion inhibitors include sulfur compounds and phosphorus compounds. Oxidation inhibitors include aromatic amine and phenol derivatives. Specific examples of bearing corrosion inhibitors include diamylphenol sulfide, zinc methyl cyclohexyl dithiophosphate and phosphorus pentasulfide-pinene reaction product. Detergent additives include calcium and barium petroleum sulfonates, aluminum dicetyl phenate and barium and calcium salts of sulfurized phenates. An especially preferred detergent is the calcium petroleum sulfonate disclosed and claimed in copending application Serial No. 222,357, filed September 10, 1962, now US. Patent No. 3,135,693, by W. B. Whitney et a1. Pour point depressants include condensation products of paraffin wax and naphthalene such as phenol-tetrawax condensation product and high molecular weight polymerization products of the esters of methacrylic acid and higher fatty alcohols such as cetyl and lauryl alcohols. Rust inhibitors include sodium salts of petroleum sulfonic acids, amine salts of naphthenic acids, primary and secondary amines, and superbased calcium and barium sulfonates.

Bearing corrosion inhibitors and oxidation inhibitors are usually ineffective as rust inhibitors. Alkaline earth petroleum sulfonates provide a measure of rust protec' tion that is often sufiicient for the intended service of a lubricating oil; however some service requirements demand additional rusting inhibition. Extended periods of operation between oil changes in automobiles require better rust performance in motor oils. The additive of this invention provides this extra measure of rust protection.

Therefore it is an object of this invention to provide a lubricating oil containing a rust inhibitor. It is also an object of this invention to provide a method for inhibiting rusting of ferruginous metals in contact with a motor oil. The provision of a lubricating composition containing an anti-rusting additive along with other additives in a motor oil is a further object of this invention. Other objects and advantages of the invention will become apparent to one skilled in the art upon studying this disclosure including the detailed description of the invention.

Broadly, the invention contemplates an antirusting 3,277,003 Patented Oct. 4, 1966 wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl, and combinations of alkyl, aryl and cycloalkyl radicals wherein each R contains from about 1 to 30 carbon atoms and wherein at least one R is an alkyl group containing from about 12 to 30 carbon atoms. The tertiary amine oxides are known and are prepared by oxidation of the corresponding tertiary amine using an oxidizing agent such as hydrogen peroxide, sodium peroxide, ozone, peracids, and the like.

Examples of such tertiary amine oxides include: dodecyldimethylamine oxide, dimethyleicoslyamine oxide, diisopropylheptadecylamine oxide, tridodecylamine oxide, lauryldibenzylamine oxide, stearyldi(4-dodecylbenzyl)- amine oxide, cyclohexyldioctadecylamine oxide, tetradecyldi(3 -cyclopentylphenyl)amine oxide, eicosylmethyl- (2,4,6-triethylbenzyl)amine oxide, dihexadecylphenylamine oxide and the like. Additionally, commercially available tertiary amines containing an alkyl radical having 12 to 30 carbon atoms such as those derived from naturally occurring materials such as tallow, coconut oil and soybean oil can be oxidized to form the tertiary amine oxides of this invention.

The amine oxide antirusting additive of the invention can be added to any petroleum-based lubricating composition such as motor oil, slushing oil, turbine oil, wire rope lubricant, fluid greases, block greases, gear oils, 2-cycle oils, and the like, wherein additives are incorporated to provide the desired lubricating composition. The antirusting additive has particular utility in motor oils such as those using, as a base stock, a hydrocarbon oil derived from a paraffinic, naphthenic or intermediate crude oil such as Pennsylvania, Mid-Continent or Coastal stock or mixtures thereof and preferably base stocks which have been highly refined. The viscosity of these oils will vary from about 50 SUS at F. to 200 SUS at 210 F. The motor oil compositions will usually contain, in addition to the antirust additive, conventional additives such as viscosity index improvers, antioxidants or bearing corrosion inhibitors, thickeners, pour point modifiers, detergents, film strength agents, dyes, and the like. The antirust additive of the invention has no appreciable effect on viscosity, pour point or other properties of the lubricating oil and therefore incorporation of the antirust additive of the invention in a lubricating oil composition will not affect the proportions of additives conventionally used in a given lubricating oil composition.

The amine oxide rust inhibitor of the invention can be used in lubricating compositions in amounts of from about 0.001 to about 5 weight percent and will usually be incorporated in lubricating compositions in amounts of about 0.1 to 1 weight percent because the preferred range will provide adequate protection in substantially all cases. The amine oxides of the invention, being oil soluble, can be added directly to the lubricating oil composition in the desired amount. The amine oxides can be mixed with other additives to form a single additive composition, e.g., about 0.001 to 5 parts by weight of amine oxide, about 0.1 to 15 parts by weight of an oil-soluble detergent, and about 0.1 to 2 parts by weight of a bearing corrosion inhibitor.

The operation of the invention is illustrated by the following specific example which should be construed as merely illustrative and not as unduly limiting the invention.

$3 EXAMPLE Normal-dodecyldimethylamine oxide was added to a commercial motor oil containing about 0.9 percent of a zinc dithiophosphate compound identified as Lubrisol 1360, and about 4 percent calcium petroleum sulfonate made according to the process disclosed in copending application Serial No. 222,357, now US. Patent No. 3,- 135,693. Several levels of concentration of the amine oxide in the oil were prepared and the lubricating com positions were tested in the Sohio rust test. This test is a modified ASTM D665 procedure in that the specimen is exposed to a l-percent acetic acid solution. The results of the tests are shown in the following table.

Table Amine oxide in lubricant, Sohio rust rating weight percent: (10=clean) 4.0 0.2 4.5

These data show that a lubricating oil composition containing n-dodecyldimethylamine oxide offers a high degree of protection against rust formation on ferruginous meta-ls in contact with the lubricating oil composition.

That which is claimed is:

1. A motor oil comprising a petroleum lubricating base stock containing a minor amount, sufficient to impart detergency of a calcium petroleum sulfonate detergent; a minor amount, sufficient to inhibit bearing corrosion of a zinc dithiophosphate bearing corrosion inhibitor; and n-dodecyldimethylamine oxide in an amount sufiicient to inhibit rusting of ferruginous metal.

2. A method of protecting internal surfaces of an internal combustion motor from rust which comprises incorporating about 0.1 to 1 weight percent of n-dodecyldimethylamine oxide in a lubricating oil composition; and lubricating the motor with the resulting composition.

3. The method of inhibiting rusting of the internal metal surfaces of an internal combustion motor which comprises incorporating about 0.1 to 1 Weight percent of a tertiary amine oxide having the structural formula wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl, and combinations of alkyl, aryl and cycloalkyl radicals having from 1 to 30 carbon atoms and. wherein at least one R is an alkyl radical containing about 12 to .30 carbon atoms in a lubricating oil composition; and lubricating the internal surfaces of the motor with the resulting composition.

4. The method of inhibiting rusting of a metal in contact with a lubricating composition which comprises incorporating in said composition a rust inhibiting amount of a tertiary amine oxide having the structural formula:

R 11-1 140 it wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl and combinations of alkyl, aryl and cycloalkyl radicals having from 1 to 30 carbon atoms and wherein at least one R is an alkyl radical containing about 12 to 30 carbon atoms and contacting said metal with the composition.

4 5. A lubricating composition comprising a major amount of lubricating oil composition and a minor amount, sufiicient to inhibit rusting of metals in contact with said lubricating composition of a tertiary amine oxide having the structural formula:

wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl, and combinations of alkyl, aryl and cycloalkyl radicals having from 1 to 30 carbon atoms and wherein at least one R is an alkyl radical containing about 12 to 30 carbon atoms.

7. A lubricating composition comprising a petroleum lubricating oil base stock containing about 0J1 to 15 weight percent of a detergent additive; about 0.1 to 2 weight percent of a bearing corrosion inhibitor; and about 0.001 to 5 Weight percent of a teritary amine oxide having the structural formula:

wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl, and combinations of alkyl, aryl and cycloalkyl radicals having from 1 to 30* carbon atoms and wherein at least one R is an alkyl radical containing about 12 to 30 carbon atoms.

8. A lubricating oil additive composition comprising about 0.1 to 15 parts by weight of a lubricating oil detergent; about 0.1 to 2 parts by weight of a bearing corrosion inhibitor; and about 0.001 to 5 parts by weight of a tertiary amine oxide having the structural formula:

wherein R is selected from the group consisting of alkyl, aryl, cycloalkyl, and combinations of alkyl, aryl and cycloalkyl radicals having from 1 to 30 carbon atoms and wherein at least one R is an alkyl radical containing about 12 to 30 carbon atoms.

References Cited by the Examiner UNITED STATES PATENTS 2,402,325 6/ 1946 Griesinger et a1 25233 3,007,784 l11/1961 Ebner 25251.5 X

FOREIGN PATENTS 866,502 4/1961 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner. 

1. A MOTOR OIL COMPRISING A PETROLEUM LUBRICATING BASE STOCK CONTAINING A MINOR AMOUNT, SUFFICIENT TO IMPART DETERGENCY OF A CALCIUM PETROLEUM SULFONATE DETERGENT; A MINOR AMOUNT, SUFFICIENT TO INHIBIT BEARING CORROSION OF A ZINC DITHIOPHOSPHATE BEARING CORROSION INHIBITOR; AND N-DODECYLIDIMETHYLAMINE OXIDE IN AN AMOUNT SUFFICIENT TO INHIBIT RUSTING OF FERRUGINOUS METAL. 